Saturday, August 17, 2013

Lead Leads The Pack

In January, Mother Jones' Kevin Drum included "the end of the crack epidemic, changes in policing tactics, higher incarceration rates, and more" as explanations for the drop in violent crime over the past two decades.
This past week, he noted as explanations for the continuing (but declining) disparity between the crime rate of black teens and that of white teens as "the toxic legacy of racism and slavery; poverty rates in inner cities; gang culture; and many more."

The "more" and the "many more" ought to include abortion and the persistent and growing dissolution of the traditional family. But that is mere quibbling, given that those are but two of numerous factors, including those cited by Drum.

But Drum's focus has been the influence of lead. In an article last winter, he linked to one study which he summarized as finding

that lead exposure is linked to production of the brain's white matter—primarily a substance called myelin, which forms an insulating sheath around the connections between neurons. Lead exposure degrades both the formation and structure of myelin, and when this happens, says Kim Dietrich, one of the leaders of the imaging studies, "neurons are not communicating effectively." Put simply, the network connections within the brain become both slower and less coordinated.

Drum linked to a second study he noted

found that high exposure to lead during childhood was linked to a permanent loss of gray matter in the prefrontal cortex—a part of the brain associated with aggression control as well as what psychologists call "executive functions": emotional regulation, impulse control, attention, verbal reasoning, and mental flexibility. One way to understand this, says Kim Cecil, another member of the Cincinnati team, is that lead affects precisely the areas of the brain "that make us most human."

The scourge of violent crime has abated since the early 1990s. Violent crime had continued to rise through the decades until 15-20 years after environmental regulations and introduction of the catalytic converter led to a dramatic decline in use of leaded gasoline in the U.S.A. States which experienced the greatest decline in lead consumption enjoyed the greatest drop in crime while countries which least reduced lead ingestion( in which lead poisoning had been rare) experienced a minimal reduction. Crime rates in neighborhoods in American cities tracked closely with lead concentrations and elevated childhood lead levels were associated with a higher incidence of arrest in children followed from womb to adulthood.

What science explained, experience confirmed. The evidence was overwhelming.

Drum had given considerable credit to several researchers, including Rick Nevin, then an economist working at HUD on the costs and benefits of removing lead paint from old homes. (See graph below from Nevin and CDC displaying corrrelation between blood level of young children and I.Q. from 1976 to 1995.) Responding to the death of Trayvon Martin, Nevin has released a study (to which Drum links) which illustrates the dramatic decline in arrests of black juveniles from 1994 to 2010, coupled with the far lower rate of decline in arrests of white juveniles. And he explains

African-American boys disproportionately involved in the criminal justice system were also disproportionately exposed to lead contaminated dust as young children, because black children were disproportionately concentrated in large cities and older housing. In 1976-1980, 15.3% of black children under the age of three had blood lead above 30 mcg/dl (micrograms of lead per deciliter of blood), when just 2.5% of white children had blood lead that high. In 1988-1991, after the elimination of leaded gasoline, 1.4% of black children and 0.4% of white children under the age of three had blood lead above 25 mcg/dl.

"The change," Nevin found, "is not explained by changes in the African-American family, poverty, or rising incarceration," which shifted far less in the period studied.

In some future time, the "right" person will make the discovery that lead had a very powerful impact on the incidence of criminality in society, and give little credit to Rick Nevin, Kevin Drum, and others who will have brought it to our attention much earlier. But the bill passed in July by the (GOP-controlled) House Appropriations Committee cuts by more than half programs to remove lead from the more than 200,000 homes in which it remains 35 leads after lead paint was banned. Harry Stein argues

According to a 2009 study, “For every dollar spent on controlling lead hazards, $17–$221 would be returned in health benefits, increased IQ, higher lifetime earnings, tax revenue, reduced spending on special education, and reduced criminal activity.” Using the most conservative estimate of $17 in benefits for every dollar invested, the $6 million that sequestration already cut from lead removal programs will cost our country at least $102 million. The House Republican cut of $64 million below sequestration would cost over $1 billion.

Clearly Repub congressional leadership is not aware of those consequences. If it were, thelead abatement program might have been completely eliminated.